In Austin, passengers were able to speed up check-in times by as much as 55 percent by using the machines, Stumbo said.

Passengers will still be able to have their bags checked and tagged by an agent if they don't choose the self-serve option.

Under the self-service option, passengers use kiosks to print checked baggage tags during the check-in process. Here's how it works:

When checking in at a kiosk, customers input their number of checked bags, pay any necessary charges, print the bag tag(s) and place the tag(s) on their luggage.

Customers then take their tagged bags to a designated agent to scan their boarding pass, verify IDs and take the bags for inspection and boarding.

Fliers are then free to head to their departure gate.

American plans to launch self-tag at additional airports in 2013, including Atlanta, Los Angeles, New York JFK, Miami, Boston, San Francisco, St. Louis and San Francisco. Other upcoming airports are Chicago O'Hare International Airport and Washington Reagan National Airport.

The former Continental Airlines, now merged with United, also tested similar DIY boarding equipment at its hub at Houston's George Bush Intercontinental Airport in previous years. And Lufthansa has been actively using self-service boarding gates for years at airports across Europe. United's parent is United Continental Holdings .

Reduced Airport Staffing?

"With this new service, our skilled agents will now be able to devote more time to customers who require extra help," said Stumbo of American.

But as more airlines roll out DIY machines, it could lead to reduced staffing at airports, one analyst says.

"By allowing those travelers who feel comfortable to tag their own bags or scan their own boarding passes, airlines can avoid hiring and training additional employees in the near term," said Henry Harteveldt, veteran airline and travel industry analyst and co-founder of Atmosphere Research Group. "In the long term, it may lead to the redeployment of staff or reduction in airport employee head count."

According to American's Stumbo, "... while we can't speak to exact dates for when/if self-tagging will become an industry standard, we do feel it will become increasingly popular within the next few years. The kiosks that you see so many airlines using nowadays are evolving just as the ATM did years ago."